This invention generally relates to devices and methods for performing a vascular anastomosis, and more particularly to stents for securing a graft vessel to a target vessel.
Vascular anastomoses, in which two vessels within a patient are surgically joined together to form a continuous channel, are required for a variety of conditions including coronary artery disease, diseases of the great and peripheral vessels, organ transplantation, and trauma. For example, in coronary artery disease (CAD), an occlusion or stenosis in a coronary artery interferes with blood flow to the heart muscle. In order to restore adequate blood flow to the heart, a graft vessel in the form of a prosthesis or harvested artery or vein is used to reroute blood flow around the occlusion. The treatment, known as coronary artery bypass grafting (CABG), can be highly traumatic to the patient's system.
In conventional CABG a large incision is made in the chest and the sternum is sawed in half to allow access to the heart. In addition, cardiopulmonary bypass, in which the patient's blood is circulated outside of the body through a heart-lung machine, is used so that the heart can be stopped and the anastomosis performed. In order to minimize the trauma to the patient's system induced by conventional CABG, less invasive techniques have been developed in which the surgery is performed through small incisions in the patient's chest with the aid of visualizing scopes. Less invasive CABG can be performed on a beating or a non-beating heart and thus may avoid the need for cardiopulmonary bypass.
In both conventional and less invasive CABG, the surgeon has to suture the graft vessel in place between the coronary artery and a blood supplying vein or artery. The suturing procedure is a time consuming, difficult process requiring a high level of surgical skill. In order to perform the suturing procedure, the surgeon must have relatively unobstructed access to the anastomotic site within the patient. As a result, in less invasive approaches which provide only limited access to the patient's vessels, some of the major coronary vessels cannot be reached adequately, which can result in incomplete revascularization and a resulting negative effect on patient survival. Moreover, certain target vessels, such as heavily calcified coronary vessels, vessels having a very small diameter of less than about 1 mm, and previously bypassed vessels, may make the suturing process difficult or impossible, so that a sutured anastomosis is not possible.
Additionally, a common problem with CABG has been the formation of thrombi and atherosclerotic lesions at and around the grafted artery, which can result in the reoccurrence of ischemia. Moreover, second operations necessitated by the reoccurrence of arterial occlusions are technically more difficult and risky due to the presence of the initial bypass. For example, surgeons have found it difficult to saw the sternum in half during the next operation without damaging the graft vessels from the first bypass which are positioned behind the sternum.
Therefore, it would be a significant advance to provide a sutureless vascular anastomosis in which the graft vessels can be positioned on a variety of locations on target vessels having a variety of different diameters, which is easily performed, and which minimizes thrombosis associated with the anastomosis. The present invention satisfies these and other needs.